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Allergies Health Center

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Skin Testing for Indoor Allergies

Even if you’re sure you’re allergic to something other than pollen, you may want to think about getting tested. Knowing what’s triggering your allergies -- pet dander, dust mites, mold, cockroaches -- can help you better protect yourself and control your symptoms.

How Allergy Skin Tests Work

When you breathe in something you're allergic to, like pet dander, your immune system overreacts. You may have swelling, itchy eyes, and a runny nose -- or more serious symptoms.

Skin testing also triggers an allergic reaction, but only on your skin. The doctor places a tiny amount of the allergen on your skin, usually on your back or forearm, and then pricks or scratches the skin underneath. It's safe and fairly painless.

If nothing happens, you’re not allergic to that trigger. If you are, you’ll get a small, raised bump that itches like a mosquito bite. That's how your doctor can tell what's causing your symptoms.

What to Expect

Before your doctor does a skin test, he will give you a physical exam and ask questions to get a sense of what triggers your allergies. Your doctor will probably test for many allergens at once.

Skin tests are accurate, but they're not perfect. It's important to work with a board-certified allergist who has a lot of experience with allergy testing.

Skin Testing Side Effects

If your body reacts to the allergen, you'll have swelling and some itchiness at the site of the skin prick. These symptoms usually start within 15 minutes and fade within 30 minutes.

Rarely, some people have a delayed reaction at the skin prick site 24 to 48 hours later.

More serious allergic reactions are very rare. To be safe, doctors always do allergy testing in an office where they can watch you.

Skin Testing: Next Steps

After skin testing, your doctor can tailor your treatment and give you advice on what to do next. You may need:

  • More testing. If results weren't clear, your doctor may want to do more testing. Some people need blood tests or challenge testing, in which you inhale small amounts of the allergen.
  • Changes at home. Once you know what you're allergic to, you can take steps to protect yourself. For instance, if you're allergic to dust mites, you can wrap your mattress in an allergen-proof cover to keep them out.
  • Medication or allergy shots. Your doctor may prescribe medicine to control your symptoms. Allergy shots can also help reduce or even get rid of your symptoms, although they take much longer to work.

WebMD Medical Reference

Reviewed by Luqman Seidu, MD on October 26, 2014

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